fs/btrfs/zlib.c

   1 /*
   2  * Copyright (C) 2008 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  *
  18  * Based on jffs2 zlib code:
  19  * Copyright © 2001-2007 Red Hat, Inc.
  20  * Created by David Woodhouse <dwmw2@infradead.org>
  21  */
  22
  23 #include <linux/kernel.h>
  24 #include <linux/slab.h>
  25 #include <linux/zlib.h>
  26 #include <linux/zutil.h>
  27 #include <linux/mm.h>
  28 #include <linux/init.h>
  29 #include <linux/err.h>
  30 #include <linux/sched.h>
  31 #include <linux/pagemap.h>
  32 #include <linux/bio.h>
  33 #include <linux/refcount.h>
  34 #include "compression.h"
  35
  36 struct workspace {
  37         z_stream strm;
  38         char *buf;
  39         struct list_head list;
  40 };
  41
  42 static void zlib_free_workspace(struct list_head *ws)
  43 {
  44         struct workspace *workspace = list_entry(ws, struct workspace, list);
  45
  46         kvfree(workspace->strm.workspace);
  47         kfree(workspace->buf);
  48         kfree(workspace);
  49 }
  50
  51 static struct list_head *zlib_alloc_workspace(void)
  52 {
  53         struct workspace *workspace;
  54         int workspacesize;
  55
  56         workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
  57         if (!workspace)
  58                 return ERR_PTR(-ENOMEM);
  59
  60         workspacesize = max(zlib_deflate_workspacesize(MAX_WBITS, MAX_MEM_LEVEL),
  61                         zlib_inflate_workspacesize());
  62         workspace->strm.workspace = kvmalloc(workspacesize, GFP_KERNEL);
  63         workspace->buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
  64         if (!workspace->strm.workspace || !workspace->buf)
  65                 goto fail;
  66
  67         INIT_LIST_HEAD(&workspace->list);
  68
  69         return &workspace->list;
  70 fail:
  71         zlib_free_workspace(&workspace->list);
  72         return ERR_PTR(-ENOMEM);
  73 }
  74
  75 static int zlib_compress_pages(struct list_head *ws,
  76                                struct address_space *mapping,
  77                                u64 start,
  78                                struct page **pages,
  79                                unsigned long *out_pages,
  80                                unsigned long *total_in,
  81                                unsigned long *total_out)
  82 {
  83         struct workspace *workspace = list_entry(ws, struct workspace, list);
  84         int ret;
  85         char *data_in;
  86         char *cpage_out;
  87         int nr_pages = 0;
  88         struct page *in_page = NULL;
  89         struct page *out_page = NULL;
  90         unsigned long bytes_left;
  91         unsigned long len = *total_out;
  92         unsigned long nr_dest_pages = *out_pages;
  93         const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
  94
  95         *out_pages = 0;
  96         *total_out = 0;
  97         *total_in = 0;
  98
  99         if (Z_OK != zlib_deflateInit(&workspace->strm, 3)) {
 100                 pr_warn("BTRFS: deflateInit failed\n");
 101                 ret = -EIO;
 102                 goto out;
 103         }
 104
 105         workspace->strm.total_in = 0;
 106         workspace->strm.total_out = 0;
 107
 108         in_page = find_get_page(mapping, start >> PAGE_SHIFT);
 109         data_in = kmap(in_page);
 110
 111         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 112         if (out_page == NULL) {
 113                 ret = -ENOMEM;
 114                 goto out;
 115         }
 116         cpage_out = kmap(out_page);
 117         pages[0] = out_page;
 118         nr_pages = 1;
 119
 120         workspace->strm.next_in = data_in;
 121         workspace->strm.next_out = cpage_out;
 122         workspace->strm.avail_out = PAGE_SIZE;
 123         workspace->strm.avail_in = min(len, PAGE_SIZE);
 124
 125         while (workspace->strm.total_in < len) {
 126                 ret = zlib_deflate(&workspace->strm, Z_SYNC_FLUSH);
 127                 if (ret != Z_OK) {
 128                         pr_debug("BTRFS: deflate in loop returned %d\n",
 129                                ret);
 130                         zlib_deflateEnd(&workspace->strm);
 131                         ret = -EIO;
 132                         goto out;
 133                 }
 134
 135                 /* we're making it bigger, give up */
 136                 if (workspace->strm.total_in > 8192 &&
 137                     workspace->strm.total_in <
 138                     workspace->strm.total_out) {
 139                         ret = -E2BIG;
 140                         goto out;
 141                 }
 142                 /* we need another page for writing out.  Test this
 143                  * before the total_in so we will pull in a new page for
 144                  * the stream end if required
 145                  */
 146                 if (workspace->strm.avail_out == 0) {
 147                         kunmap(out_page);
 148                         if (nr_pages == nr_dest_pages) {
 149                                 out_page = NULL;
 150                                 ret = -E2BIG;
 151                                 goto out;
 152                         }
 153                         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 154                         if (out_page == NULL) {
 155                                 ret = -ENOMEM;
 156                                 goto out;
 157                         }
 158                         cpage_out = kmap(out_page);
 159                         pages[nr_pages] = out_page;
 160                         nr_pages++;
 161                         workspace->strm.avail_out = PAGE_SIZE;
 162                         workspace->strm.next_out = cpage_out;
 163                 }
 164                 /* we're all done */
 165                 if (workspace->strm.total_in >= len)
 166                         break;
 167
 168                 /* we've read in a full page, get a new one */
 169                 if (workspace->strm.avail_in == 0) {
 170                         if (workspace->strm.total_out > max_out)
 171                                 break;
 172
 173                         bytes_left = len - workspace->strm.total_in;
 174                         kunmap(in_page);
 175                         put_page(in_page);
 176
 177                         start += PAGE_SIZE;
 178                         in_page = find_get_page(mapping,
 179                                                 start >> PAGE_SHIFT);
 180                         data_in = kmap(in_page);
 181                         workspace->strm.avail_in = min(bytes_left,
 182                                                            PAGE_SIZE);
 183                         workspace->strm.next_in = data_in;
 184                 }
 185         }
 186         workspace->strm.avail_in = 0;
 187         ret = zlib_deflate(&workspace->strm, Z_FINISH);
 188         zlib_deflateEnd(&workspace->strm);
 189
 190         if (ret != Z_STREAM_END) {
 191                 ret = -EIO;
 192                 goto out;
 193         }
 194
 195         if (workspace->strm.total_out >= workspace->strm.total_in) {
 196                 ret = -E2BIG;
 197                 goto out;
 198         }
 199
 200         ret = 0;
 201         *total_out = workspace->strm.total_out;
 202         *total_in = workspace->strm.total_in;
 203 out:
 204         *out_pages = nr_pages;
 205         if (out_page)
 206                 kunmap(out_page);
 207
 208         if (in_page) {
 209                 kunmap(in_page);
 210                 put_page(in_page);
 211         }
 212         return ret;
 213 }
 214
 215 static int zlib_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 216 {
 217         struct workspace *workspace = list_entry(ws, struct workspace, list);
 218         int ret = 0, ret2;
 219         int wbits = MAX_WBITS;
 220         char *data_in;
 221         size_t total_out = 0;
 222         unsigned long page_in_index = 0;
 223         size_t srclen = cb->compressed_len;
 224         unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
 225         unsigned long buf_start;
 226         struct page **pages_in = cb->compressed_pages;
 227         u64 disk_start = cb->start;
 228         struct bio *orig_bio = cb->orig_bio;
 229
 230         data_in = kmap(pages_in[page_in_index]);
 231         workspace->strm.next_in = data_in;
 232         workspace->strm.avail_in = min_t(size_t, srclen, PAGE_SIZE);
 233         workspace->strm.total_in = 0;
 234
 235         workspace->strm.total_out = 0;
 236         workspace->strm.next_out = workspace->buf;
 237         workspace->strm.avail_out = PAGE_SIZE;
 238
 239         /* If it's deflate, and it's got no preset dictionary, then
 240            we can tell zlib to skip the adler32 check. */
 241         if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
 242             ((data_in[0] & 0x0f) == Z_DEFLATED) &&
 243             !(((data_in[0]<<8) + data_in[1]) % 31)) {
 244
 245                 wbits = -((data_in[0] >> 4) + 8);
 246                 workspace->strm.next_in += 2;
 247                 workspace->strm.avail_in -= 2;
 248         }
 249
 250         if (Z_OK != zlib_inflateInit2(&workspace->strm, wbits)) {
 251                 pr_warn("BTRFS: inflateInit failed\n");
 252                 kunmap(pages_in[page_in_index]);
 253                 return -EIO;
 254         }
 255         while (workspace->strm.total_in < srclen) {
 256                 ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH);
 257                 if (ret != Z_OK && ret != Z_STREAM_END)
 258                         break;
 259
 260                 buf_start = total_out;
 261                 total_out = workspace->strm.total_out;
 262
 263                 /* we didn't make progress in this inflate call, we're done */
 264                 if (buf_start == total_out)
 265                         break;
 266
 267                 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
 268                                                  total_out, disk_start,
 269                                                  orig_bio);
 270                 if (ret2 == 0) {
 271                         ret = 0;
 272                         goto done;
 273                 }
 274
 275                 workspace->strm.next_out = workspace->buf;
 276                 workspace->strm.avail_out = PAGE_SIZE;
 277
 278                 if (workspace->strm.avail_in == 0) {
 279                         unsigned long tmp;
 280                         kunmap(pages_in[page_in_index]);
 281                         page_in_index++;
 282                         if (page_in_index >= total_pages_in) {
 283                                 data_in = NULL;
 284                                 break;
 285                         }
 286                         data_in = kmap(pages_in[page_in_index]);
 287                         workspace->strm.next_in = data_in;
 288                         tmp = srclen - workspace->strm.total_in;
 289                         workspace->strm.avail_in = min(tmp,
 290                                                            PAGE_SIZE);
 291                 }
 292         }
 293         if (ret != Z_STREAM_END)
 294                 ret = -EIO;
 295         else
 296                 ret = 0;
 297 done:
 298         zlib_inflateEnd(&workspace->strm);
 299         if (data_in)
 300                 kunmap(pages_in[page_in_index]);
 301         if (!ret)
 302                 zero_fill_bio(orig_bio);
 303         return ret;
 304 }
 305
 306 static int zlib_decompress(struct list_head *ws, unsigned char *data_in,
 307                            struct page *dest_page,
 308                            unsigned long start_byte,
 309                            size_t srclen, size_t destlen)
 310 {
 311         struct workspace *workspace = list_entry(ws, struct workspace, list);
 312         int ret = 0;
 313         int wbits = MAX_WBITS;
 314         unsigned long bytes_left;
 315         unsigned long total_out = 0;
 316         unsigned long pg_offset = 0;
 317         char *kaddr;
 318
 319         destlen = min_t(unsigned long, destlen, PAGE_SIZE);
 320         bytes_left = destlen;
 321
 322         workspace->strm.next_in = data_in;
 323         workspace->strm.avail_in = srclen;
 324         workspace->strm.total_in = 0;
 325
 326         workspace->strm.next_out = workspace->buf;
 327         workspace->strm.avail_out = PAGE_SIZE;
 328         workspace->strm.total_out = 0;
 329         /* If it's deflate, and it's got no preset dictionary, then
 330            we can tell zlib to skip the adler32 check. */
 331         if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
 332             ((data_in[0] & 0x0f) == Z_DEFLATED) &&
 333             !(((data_in[0]<<8) + data_in[1]) % 31)) {
 334
 335                 wbits = -((data_in[0] >> 4) + 8);
 336                 workspace->strm.next_in += 2;
 337                 workspace->strm.avail_in -= 2;
 338         }
 339
 340         if (Z_OK != zlib_inflateInit2(&workspace->strm, wbits)) {
 341                 pr_warn("BTRFS: inflateInit failed\n");
 342                 return -EIO;
 343         }
 344
 345         while (bytes_left > 0) {
 346                 unsigned long buf_start;
 347                 unsigned long buf_offset;
 348                 unsigned long bytes;
 349
 350                 ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH);
 351                 if (ret != Z_OK && ret != Z_STREAM_END)
 352                         break;
 353
 354                 buf_start = total_out;
 355                 total_out = workspace->strm.total_out;
 356
 357                 if (total_out == buf_start) {
 358                         ret = -EIO;
 359                         break;
 360                 }
 361
 362                 if (total_out <= start_byte)
 363                         goto next;
 364
 365                 if (total_out > start_byte && buf_start < start_byte)
 366                         buf_offset = start_byte - buf_start;
 367                 else
 368                         buf_offset = 0;
 369
 370                 bytes = min(PAGE_SIZE - pg_offset,
 371                             PAGE_SIZE - buf_offset);
 372                 bytes = min(bytes, bytes_left);
 373
 374                 kaddr = kmap_atomic(dest_page);
 375                 memcpy(kaddr + pg_offset, workspace->buf + buf_offset, bytes);
 376                 kunmap_atomic(kaddr);
 377
 378                 pg_offset += bytes;
 379                 bytes_left -= bytes;
 380 next:
 381                 workspace->strm.next_out = workspace->buf;
 382                 workspace->strm.avail_out = PAGE_SIZE;
 383         }
 384
 385         if (ret != Z_STREAM_END && bytes_left != 0)
 386                 ret = -EIO;
 387         else
 388                 ret = 0;
 389
 390         zlib_inflateEnd(&workspace->strm);
 391
 392         /*
 393          * this should only happen if zlib returned fewer bytes than we
 394          * expected.  btrfs_get_block is responsible for zeroing from the
 395          * end of the inline extent (destlen) to the end of the page
 396          */
 397         if (pg_offset < destlen) {
 398                 kaddr = kmap_atomic(dest_page);
 399                 memset(kaddr + pg_offset, 0, destlen - pg_offset);
 400                 kunmap_atomic(kaddr);
 401         }
 402         return ret;
 403 }
 404
 405 const struct btrfs_compress_op btrfs_zlib_compress = {
 406         .alloc_workspace        = zlib_alloc_workspace,
 407         .free_workspace         = zlib_free_workspace,
 408         .compress_pages         = zlib_compress_pages,
 409         .decompress_bio         = zlib_decompress_bio,
 410         .decompress             = zlib_decompress,
 411 };